LinearElement 是Linear Geometry SDK中所有线性几何类的基类，提供了线性几何的常用操作函数，集体内容如下：
1.修剪和延长类函数：ExtendXXX 和 ExtendOrTrimXXX
ExtendBeginByLineOrTrim ：通过直线修补方式延长或修剪曲线的起始端；
代码如下：
LinearElement ExtendBeginByLineOrTrim_Demo(LinearElement sourceLinear)
{
LinearElement resultLinear = null;
double extTrimLength = 100;
resultLinear = sourceLinear.ExtendBeginByLineOrTrim(extTrimLength);
return resultLinear;
}
参数含义：变量extTrimLength 如果为正，对路线起始位置进行延长，变量extTrimLength 为负值，则对路线起始位置进行剪切。
ExtendOrTrimBegin：按长度延长或修剪曲线的起始端；
代码如下：
LinearElement ExtendOrTrimBegin_Demo(LinearElement sourceLinear)
{
LinearElement resultLinear = null;
double extTrimLength = -100;
resultLinear = sourceLinear.ExtendOrTrimBegin(extTrimLength);
return resultLinear;
}
参数含义：extTrimLength 如果为正，对路线起始位置进行延长，变量extTrimLength 为负值，则对路线起始位置进行剪切。
ExtendOrTrimBeginByParameter ：通过沿路线参数（系数）延长或修剪曲线的起始端；
代码如下：
LinearElement ExtendOrTrimBeginByParameter_Demo(LinearElement sourceLinear)
{
LinearElement resultLinear = null;
double parameter = 100;
resultLinear = sourceLinear.ExtendOrTrimBeginByParameter(parameter);
return resultLinear;
}
参数含义：extTrimLength 如果为正，对路线起始位置进行延长，变量extTrimLength 为负值，则对路线起始位置进行剪切。
ExtendOrTrimBeginByPoint：将曲线起始端延长或修剪到指定的点；
代码如下：
LinearElement ExtendOrTrimBeginByPoint_Demo(LinearElement sourceLinear)
{
LinearElement resultLinear = null;
//DPoint3d extPoint = new DPoint3d(11094.0, 4358.0);
DPoint3d extPoint = new DPoint3d(8649.0, 1545.0);
resultLinear = sourceLinear.ExtendOrTrimBeginByPoint(extPoint);
return resultLinear;
}
参数含义：extPoint为剪切点，如果点与路线的垂足在路线范围内，则对路线起始位置进行剪切，如果点与路线的垂足在路线范围外，则对路线起始位置进行延长。
ExtendEndByLineOrTrim：通过直线修补方式延长或修剪曲线的终止端；
代码如下：
LinearElement ExtendEndByLineOrTrim_Demo(LinearElement sourceLinear)
{
LinearElement resultLinear = null;
double extTrimLength = 100;
resultLinear = sourceLinear.ExtendEndByLineOrTrim(extTrimLength);
return resultLinear;
}
参数含义：extTrimLength 如果为正，对直线终止位置进行延长，变量extTrimLength 为负值，则对直线起始位置进行剪切。
ExtendOrTrimEnd：按长度延长或修剪曲线的终止端；
代码如下：
LinearElement ExtendOrTrimEnd_Demo(LinearElement sourceLinear)
{
LinearElement resultLinear = null;
double extTrimLength = -100;
resultLinear = sourceLinear.ExtendOrTrimEnd(extTrimLength);
return resultLinear;
}
参数含义：extTrimLength 如果为正，对路线终止位置进行延长，变量extTrimLength 为负值，则对路线终止始位置进行剪切。
ExtendOrTrimEndByParameter：通过沿路线参数（系数）延长或修剪曲线的终止端；
代码如下：
LinearElement ExtendOrTrimEnd_Demo(LinearElement sourceLinear)
{
LinearElement resultLinear = null;
double extTrimLength = -100;
resultLinear = sourceLinear.ExtendOrTrimEnd(extTrimLength);
return resultLinear;
}
参数含义：变量extTrimLength 如果为正，对路线终止位置进行延长，变量extTrimLength 为负值，则对路线终止始位置进行剪切。
ExtendOrTrimEndByPoint：将曲线终止端延长或修剪到指定的点；
代码如下：
LinearElement ExtendOrTrimEndByPoint_Demo(LinearElement sourceLinear)
{
LinearElement resultLinear = null;
//DPoint3d extPoint = new DPoint3d(11094.0, 4358.0);
DPoint3d extPoint = new DPoint3d(13419.0, 6691.0);
resultLinear = sourceLinear.ExtendOrTrimEndByPoint(extPoint);
return resultLinear;
}
参数含义：extPoint为剪切点，如果点与路线的垂足在路线范围内，则对路线终止位置进行剪切，如果点与路线的垂足在路线范围外，则对路线终止位置进行延长。
注：红色路线为原始线形，白色为红色路线水平方向平移100主单位（米）并且延长/截取后的线形。具体代码如下：
DTransform3d tra3d = new DTransform3d(1, 0, 0, 100, 0, 1, 0, 0, 0, 0, 1, 0);
resultLinear = resultLinear.Transform(tra3d);
2.距离计算和转换函数：GetChordXXX , GetDistanceAlongXXX ,
GetChordDistanceFromDistanceAlong：将曲线距离值转换为弦距离值；
代码如下：
public static double GetChordDistanceFromDistanceAlong_Demo(LinearElement sourceLinear)
{
double distance = 100;
double chordDistance = 0;
chordDistance = sourceLinear.GetChordDistanceFromDistanceAlong(distance);
return chordDistance;
}
参数含义：distance变量代表需要转换的距离值。
GetChordDistanceFromParameter：将参数值转换为弦距离值；
代码如下：
public static double GetChordDistanceFromParameter_Demo(LinearElement sourceLinear)
{
double parameter = 0.1;
double chordDistance = 0;
chordDistance = sourceLinear.GetChordDistanceFromParameter(parameter);
return chordDistance;
}
参数含义：parameter，[0-1]之间的值，代码所要获取点距起始点的距离与整条线形长度的比值。
GetDistanceAlongFromChordDistance：将曲线弦距离距离值转换为距离值；
代码如下：
public static double GetDistanceAlongFromChordDistance_Demo(LinearElement sourceLinear)
{
double chordDistance = 100;
double distanceAlong = 0;
distanceAlong = sourceLinear.GetDistanceAlongFromChordDistance(chordDistance);
return distanceAlong;
}
参数含义：chordDistance变量代表需要转换的弦距离值。
GetLength：获取曲线长度。
代码如下：
public static double GetLength_Demo(LinearElement sourceLinear)
{
double ptToPtTolerance = 0.001;
double length = 0;
length = sourceLinear.GetLength(ptToPtTolerance);
return length;
}
参数含义： ptToPtTolerance为最小精度的设置值。
3.点的计算函数：GetPointXXX ，StrokeXXX, ProjectPointXXX
GetPointAtDistanceOffset：根据距离值和偏移值获取点；
代码如下：
LinearPoint GetPointAtDistanceOffset_Demo(LinearElement sourceLinear)
{
LinearPoint resultPoint = null;
double distance = 100;
double offset = 100;
resultPoint = sourceLinear.GetPointAtDistanceOffset(distance, offset);
CreateElement.BuildPoint(resultPoint.Coordinates);
return resultPoint;
}
参数含义：distance，所要计算的点与线形的起始点的距离，offset 的值为正值时向右偏移，为负值时向左偏移。
GetPointAtParameterOffset：根据参数值和偏移值获取点；
代码如下：
LinearPoint GetPointAtParameterOffset_Demo(LinearElement sourceLinear)
{
LinearPoint resultPoint = null;
double parameter = 0.1;
double offset = 100;
resultPoint = sourceLinear.GetPointAtParameterOffset(parameter, offset);
CreateElement.BuildPoint(resultPoint.Coordinates);
return resultPoint;
}
参数含义：parameter，[0-1]之间的值，代码所要获取点距起始点的距离与整条线形长度的比值，offset 的值为正值时向右偏移，为负值时向左偏移。
ProjectPointOnPerpendicular：根据已知点计算到路线的铅直投影点；
代码如下：
LinearPoint ProjectPointOnPerpendicular_Demo(LinearElement sourceLinear)
{
LinearPoint resultPoint = null;
DPoint3d point = new DPoint3d(0, 0, 0);
resultPoint = sourceLinear.ProjectPointOnPerpendicular(point);
CreateElement.BuildPoint(resultPoint.Coordinates);
return resultPoint;
}
参数含义：point为已知点。
ProjectPointOnSkew：根据已知点，倾角及偏移值计算投影点
代码如下：
LinearPoint ProjectPointOnSkew_Demo(LinearElement sourceLinear)
{
LinearPoint resultPoint = null;
DPoint3d point = new DPoint3d(0, 0, 0);
double skewAngle = 3.14 / 2;
double offset = 100;
resultPoint = sourceLinear.ProjectPointOnSkew(point, skewAngle, offset);
CreateElement.BuildPoint(resultPoint.Coordinates);
return resultPoint;
}
参数含义：point为已知点，skewAngle 为斜交角度，offset为偏移距离当为正值时向右偏移，为负值时向左偏移。
ProjectPointOnTangent：根据已知点计算切点；
代码如下：
LinearPoint ProjectPointOnTangent_Demo(LinearElement sourceLinear)
{
LinearPoint resultPoint = null;
DPoint3d point = new DPoint3d(0, 0, 0);
resultPoint = sourceLinear.ProjectPointOnTangent(point);
CreateElement.BuildPoint(resultPoint.Coordinates);
return resultPoint;
}
参数含义：point为已知点，
StrokeByChord：根据弦距离获取点集；
代码如下：
LinearPointCollection StrokeByChord_Demo(LinearElement sourceLinear)
{
LinearPointCollection resultPoints = null;
double chordTolerance = 100;
resultPoints = sourceLinear.StrokeByChord(chordTolerance);
foreach(LinearPoint resultPoint in resultPoints)
{
CreateElement.BuildPoint(resultPoint.Coordinates);
}
return resultPoints;
}
参数含义：chordTolerance为弦距离，resultPoints为返回点集。
StrokeByConnectionPoints：根据连接点类型获取点集；
代码如下：
LinearPointCollection StrokeByConnectionPoints_Demo(LinearElement sourceLinear)
{
LinearPointCollection resultPoints = null;
ConnectionPointTypes types = ConnectionPointTypes.Spiral_Line;
resultPoints = sourceLinear.StrokeByConnectionPoints(types);
foreach (LinearPoint resultPoint in resultPoints)
{
CreateElement.BuildPoint(resultPoint.Coordinates);
}
return resultPoints;
}
参数含义：types为弦连接点类型，resultPoints为返回点集。
StrokeByDistances：根据距离获取点集；
代码如下：
LinearPointCollection StrokeByDistances_Demo(LinearElement sourceLinear)
{
LinearPointCollection resultPoints = null;
double[] distances = { 0.0, 100.0, 1000.0 };
resultPoints = sourceLinear.StrokeByDistances(distances);
foreach (LinearPoint resultPoint in resultPoints)
{
CreateElement.BuildPoint(resultPoint.Coordinates);
}
return resultPoints;
}
参数含义：distances为点与线形的起始点之间的距离，resultPoints为返回点集。
StrokeByEndPoints：获取路线的起终点集合；
代码如下：
LinearPointCollection StrokeByEndPoints_Demo(LinearElement sourceLinear)
{
LinearPointCollection resultPoints = null;
resultPoints = sourceLinear.StrokeByEndPoints();
foreach (LinearPoint resultPoint in resultPoints)
{
CreateElement.BuildPoint(resultPoint.Coordinates);
}
return resultPoints;
}
参数含义：resultPoints为返回点集。
StrokeByStep：根据增加值或者等距离值获取点集；
代码如下：
LinearPointCollection StrokeByStep_Demo(LinearElement sourceLinear)
{
LinearPointCollection resultPoints = null;
DPoint3d extPoint = new DPoint3d(0, 0);
double stepValue = 0;
StrokingByStepMethod stepMetho = StrokingByStepMethod.EqualDistance;
resultPoints = sourceLinear.StrokeByStep(stepValue, stepMetho);
foreach (LinearPoint resultPoint in resultPoints)
{
CreateElement.BuildPoint(resultPoint.Coordinates);
}
return resultPoints;
}
参数含义：resultPoints为返回点集。
4.求交和偏移函数：Intersect ，XXXOffsetElement,
Intersect：获取当前曲线与其它线的交点集；
代码如下：
LinearIntersectionCollection Intersect_Demo(LinearElement sourceLinear)
{
LinearIntersectionCollection resultPoints = null;
DPoint3d origin = new DPoint3d(12419.0, 0, 0);
DVector3d vect = new DVector3d(0, 100000, 0);
resultPoints = sourceLinear.Intersect(origin, vect);
foreach (LinearPoint resultPoint in resultPoints)
{
CreateElement.BuildPoint(resultPoint.Coordinates);
}
return resultPoints;
}
参数含义：origin为与当前曲线相交直线的起始点，vect为向量。
GetOffsetElement：获取当前曲线的偏移线；
代码如下：
LinearElement GetOffsetElement_Demo(LinearElement sourceLinear)
{
LinearElement resultLinear = null;
double offset = 100;
resultLinear = sourceLinear.GetOffsetElement(offset);
return resultLinear;
}
参数含义：offset为偏移值，返回值为LinearElement 。
GetPartialByDistances：从曲线上截取指定参数区间内的子曲线段；
代码如下：
LinearElement GetPartialByDistances_Demo(LinearElement sourceLinear)
{
LinearElement resultLinear = null;
double startDistance = 500;
double endDistance = 3000;
resultLinear = sourceLinear.GetPartialByDistances(startDistance, endDistance);
return resultLinear;
}
参数含义：startDistance为起始距离，endDistance为终止距离。
5.其他
CreateFromCurveVector：通过MS的曲线类创建；
代码如下：
protected LinearElement CreateFromCurveVector_Demo(LinearElement sourceLinear)
{
LinearElement resultLinear = null;
CurveVector curveVector;
curveVector = sourceLinear.GetCurveVector();
bool is3d = false;
resultLinear = LinearElement.CreateFromCurveVector(curveVector, is3d);
return resultLinear;
}
参数含义：curveVector为MS的曲线描述，is3d是否为三维曲线。
GetCurveVector：转换为MS的曲线类；
代码如下：
protected CurveVector GetCurveVector_Demo(LinearElement sourceLinear)
{
CurveVector cV;
cV = sourceLinear.GetCurveVector();
return cV;
}
参数含义：返回值cV为MS的曲线描述，
GetNativeElement：获得C++/CLI的对象；
GetCentroid：计算曲线所围成的区域的质心坐标；
代码如下：
protected DPoint3d GetCentroid_Demo(LinearElement sourceLinear)
{
DPoint3d resultPt;
double strokingTo = 0.01;
resultPt = sourceLinear.GetCentroid(strokingTo);
return resultPt;
}
参数含义：strokingTo为允许偏差，返回值resultPt 为质心坐标。
IsClosed：是否是封闭曲线；
代码如下：
protected bool IsClosed_Demo(LinearElement sourceLinear)
{
bool iIsClosed = false;
iIsClosed = sourceLinear.IsClosed();
return iIsClosed;
}
参数含义：返回值iIsClosed为bool变量。
ShallowCopy：浅拷贝；
代码如下：
protected LinearElement ShallowCopy_Demo(LinearElement sourceLinear)
{
LinearElement resultLinear = null;
resultLinear = sourceLinear.ShallowCopy();
return resultLinear;
}
参数含义：返回值为LinearElement 对象。
Transform：坐标变换；
代码如下：
protected LinearElement Transform_Demo(LinearElement sourceLinear)
{
LinearElement resultLinear = null;
//沿X轴正方向和Y轴负方向平移1000
DTransform3d tra3d = new DTransform3d(1, 0, 0, 1000, 0, 1, 0, -1000, 0, 0, 1, 0);
resultLinear = sourceLinear.Transform(tra3d);
CreateElement.DrawElementFromLinearElement(resultLinear);
return resultLinear;
}
参数含义：tra3d 为MS的DTransform3d 对象，
示例代码：